Camera calibration - Revision history

Jca: /* Take test images */

2024-01-23T10:36:09Z

Take test images

← Older revision		Revision as of 12:36, 23 January 2024
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	Place the pattern in front of the robot.		Place the pattern in front of the robot.

	Check using [[Robobot_software_description#View_the_stream \| motion (Video stremaer)]].		Check position using [[Robobot_software_description#View_the_stream \| motion (Video stremaer)]].

	View the stream using a browser on port 8081, like http://10.197.216.165:8081/, but with the robot IP, move the pattern (or the robot) for an appropriate view:		View the stream using a browser on port 8081, like http://10.197.216.165:8081/, but with the robot IP, move the pattern (or the robot) for an appropriate view:

Jca at 10:34, 23 January 2024

2024-01-23T10:34:43Z

← Older revision		Revision as of 12:34, 23 January 2024
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	Where px and py are the pixel position in the image; w is the scaling at this distance (z) - from meters to pixels; 1050.6 and 1046.7 are the focal lengths (f) in pixels (should be the same value for most cameras), 712.6 and 430.6 are the pixel positions in the centre of the lens. If the camera chip is mounted correctly, this is also the centre of the image.		Where px and py are the pixel position in the image; w is the scaling at this distance (z) - from meters to pixels; 1050.6 and 1046.7 are the focal lengths (f) in pixels (should be the same value for most cameras), 712.6 and 430.6 are the pixel positions in the centre of the lens. If the camera chip is mounted correctly, this is also the centre of the image.

			More details here: https://docs.opencv.org/3.4.20/dc/dbb/tutorial_py_calibration.html.

	=== Lens distortion ===		=== Lens distortion ===

Jca at 10:32, 23 January 2024

2024-01-23T10:32:01Z

← Older revision		Revision as of 12:32, 23 January 2024
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	[[File:img_raw_1.jpg \| 200px]] [[File:cam_cal_2.jpg \| 200px]] [[File:cam_cal_3.jpg \| 200px]] [[File:cam_cal_4.jpg \| 200px]] [[File:cam_cal_5.jpg \| 200px]] [[File:cam_cal_6.jpg \| 200px]] [[File:cam_cal_7.jpg \| 200px]] [[File:cam_cal_8.jpg \| 200px]]		[[File:img_raw_1.jpg \| 200px]] [[File:cam_cal_2.jpg \| 200px]] [[File:cam_cal_3.jpg \| 200px]] [[File:cam_cal_4.jpg \| 200px]] [[File:cam_cal_5.jpg \| 200px]] [[File:cam_cal_6.jpg \| 200px]] [[File:cam_cal_7.jpg \| 200px]] [[File:cam_cal_8.jpg \| 200px]]

			The run the calibration

			local@jack:~/svn/robobot/raubase/build $ ./raubase -m
			# UService:: created directory log_20240123_105137.289/
			# UService::setup: Ignoring robot hardware (Regbot and GPIO)
			# SpyVision:: disabled in robot.ini
			# Video device 0: '''width=1280, height=720''', format=MJPG, FPS=25
			# Camera is running (to stabilize illumination)
			# ready to calibrate (stopping camera)
			# UCam::run: camera released
			# 0 succes img/img_raw_20240123_101039.126.jpg
			# 1 succes img/img_raw_20240123_103400.651.jpg
			# 2 succes img/img_raw_20240123_103617.847.jpg
			# 3 succes img/img_raw_20240123_103723.998.jpg
			# 4 succes img/img_raw_20240123_103833.044.jpg
			# 5 succes img/img_raw_20240123_103925.440.jpg
			# 6 succes img/img_raw_20240123_104011.273.jpg
			# 7 succes img/img_raw_20240123_105019.243.jpg
			# Camera matrix 0: '''1050.6''' 0.0 '''712.6'''
			# Camera matrix 1: 0.0 '''1046.7''' '''430.6'''
			# Camera matrix 2: 0.0 0.0 1.0
			# Distortion k1: -0.397866
			# Distortion k2: 0.173319
			# Distortion p1: 9.58965e-05
			# Distortion p2: -0.000660305
			# Distortion k3: -0.0385043
			# '''Average pixel error is 0.26'''
			# Image 0 error 0.29 pixels
			# Image 1 error 0.20 pixels
			# Image 2 error 0.34 pixels
			# Image 3 error 0.32 pixels
			# Image 4 error 0.26 pixels
			# Image 5 error 0.16 pixels
			# Image 6 error 0.19 pixels
			# Image 7 error 0.23 pixels
			# --------- terminating -----------
			# UCam:: logfile closed
			# UService:: configuration '''saved to robot.ini'''
			local@jack:~/svn/robobot/raubase/build $

	~~@todo~~		The code for this is in the scam.cpp file in a function called bool UCam::calibrate().

			In this case, the average pixel error is calculated to 0.26 pixels.

			===Camera materix ===

			The result is a camera matrix ('''CM'''):

			# Camera matrix 0: '''1050.6''' 0.0 '''712.6'''
			# Camera matrix 1: 0.0 '''1046.7''' '''430.6'''
			# Camera matrix 2: 0.0 0.0 1.0

			The camera matrix gives the pixel position in the image for a given '''P''' = (x,y,z) position in the real world in meters
			(here, x is left, y is down, and z is the distance along the camera centre axis; the camera itself (the focal point) is at (0,0,0) in this coordinate system. i.e.:

			'''Px''' = '''CM''' * '''P'''
			or
			px/w = 1050.6 * x + 712.6
			py/w = 1046.7 * y + 430.6
			w = z

			Where px and py are the pixel position in the image; w is the scaling at this distance (z) - from meters to pixels; 1050.6 and 1046.7 are the focal lengths (f) in pixels (should be the same value for most cameras), 712.6 and 430.6 are the pixel positions in the centre of the lens. If the camera chip is mounted correctly, this is also the centre of the image.

			=== Lens distortion ===

			The lens distortion factors are found to be

			# Distortion k1: -0.397866
			# Distortion k2: 0.173319
			# Distortion p1: 9.58965e-05
			# Distortion p2: -0.000660305
			# Distortion k3: -0.0385043

			How to intrepid these can be found here: https://docs.opencv.org/3.4.20/dc/dbb/tutorial_py_calibration.html

			These factors are used to generate a rectified image (saved with the image name ''img_rec_2024...'' when saving an image), and a rectified image is available from the scam module function ''cv::Mat getFrame()'', and used like:

			cv::Mat frame = cam.getFrame();

			The raw distorted frame is also available with:

			frame = cam.getFrameRaw();


			=== Configuration file (robot.ini) ===

			The result of the calibration is saved in the configuration file in the camera section:

			[camera]
			device = 0
			width = 1280
			height = 720
			fps = 25
			matrix = 1050.6 0.0 712.6 0.0 1046.7 430.6 0.0 0.0 1.0
			distortion = -0.397866 0.173319 9.58965e-05 -0.000660305 -0.0385043

Jca at 09:50, 23 January 2024

2024-01-23T09:50:46Z

← Older revision		Revision as of 11:50, 23 January 2024
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	Repeat this for 6-10 images with the pattern all around the camera view, something like:		Repeat this for 6-10 images with the pattern all around the camera view, something like:

	[[File:img_raw_1.jpg \| 200px]] [[File:cam_cal_2.jpg \| 200px]] [[File:cam_cal_3.jpg \| 200px]] [[File:cam_cal_4.jpg \| 200px]] [[File:cam_cal_5.jpg \| 200px]] [[File:cam_cal_6.jpg \| 200px]] [[File:cam_cal_7.jpg \| 200px]]		[[File:img_raw_1.jpg \| 200px]] [[File:cam_cal_2.jpg \| 200px]] [[File:cam_cal_3.jpg \| 200px]] [[File:cam_cal_4.jpg \| 200px]] [[File:cam_cal_5.jpg \| 200px]] [[File:cam_cal_6.jpg \| 200px]] [[File:cam_cal_7.jpg \| 200px]] [[File:cam_cal_8.jpg \| 200px]]



	@todo		@todo

Jca at 09:47, 23 January 2024

2024-01-23T09:47:43Z

← Older revision		Revision as of 11:47, 23 January 2024
Line 54:		Line 54:
	Repeat this for 6-10 images with the pattern all around the camera view, something like:		Repeat this for 6-10 images with the pattern all around the camera view, something like:

	[[File:img_raw_1.jpg \| 200px]] [[File:cam_cal_2.jpg \| 200px]] [[File:cam_cal_3.jpg \| 200px]] [[File:cam_cal_4.jpg \| 200px]] [[File:cam_cal_5.jpg \| 200px]] [[File:cam_cal_6.jpg \| 200px]]		[[File:img_raw_1.jpg \| 200px]] [[File:cam_cal_2.jpg \| 200px]] [[File:cam_cal_3.jpg \| 200px]] [[File:cam_cal_4.jpg \| 200px]] [[File:cam_cal_5.jpg \| 200px]] [[File:cam_cal_6.jpg \| 200px]] [[File:cam_cal_7.jpg \| 200px]]



	@todo		@todo

Jca at 09:45, 23 January 2024

2024-01-23T09:45:25Z

← Older revision		Revision as of 11:45, 23 January 2024
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	Repeat this for 6-10 images with the pattern all around the camera view, something like:		Repeat this for 6-10 images with the pattern all around the camera view, something like:

	[[File:~~cam_cal_1~~.jpg \| 200px]] [[File:cam_cal_2.jpg \| 200px]] [[File:cam_cal_3.jpg \| 200px]] [[File:cam_cal_4.jpg \| 200px]] [[File:cam_cal_5.jpg \| 200px]] [[File:cam_cal_6.jpg \| 200px]]		[[File:img_raw_1.jpg \| 200px]] [[File:cam_cal_2.jpg \| 200px]] [[File:cam_cal_3.jpg \| 200px]] [[File:cam_cal_4.jpg \| 200px]] [[File:cam_cal_5.jpg \| 200px]] [[File:cam_cal_6.jpg \| 200px]]



	@todo		@todo

Jca at 09:43, 23 January 2024

2024-01-23T09:43:00Z

← Older revision		Revision as of 11:43, 23 January 2024
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	The raubase saves the image in an '''img''' subdirectory, and the raw image name starts with '''img_raw_2024...'''.		The raubase saves the image in an '''img''' subdirectory, and the raw image name starts with '''img_raw_2024...'''.

	Repeat this for 6-10 images with the pattern all around the camera view.		Repeat this for 6-10 images with the pattern all around the camera view, something like:

			[[File:cam_cal_1.jpg \| 200px]] [[File:cam_cal_2.jpg \| 200px]] [[File:cam_cal_3.jpg \| 200px]] [[File:cam_cal_4.jpg \| 200px]] [[File:cam_cal_5.jpg \| 200px]] [[File:cam_cal_6.jpg \| 200px]]



	@todo		@todo

Jca at 09:06, 23 January 2024

2024-01-23T09:06:19Z

← Older revision		Revision as of 11:06, 23 January 2024
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	Stop the video streamer (using ctrl-C) and let the '''raubase''' take the image.		Stop the video streamer (using ctrl-C) and let the '''raubase''' take the image.

	[[File:test_pattern_and_jack.jpg \| ~~300px~~]]		[[File:test_pattern_and_jack.jpg \| 250px]] [[File:img_raw_1.jpg \| 250px]]


	local@jack:~/svn/robobot/raubase/build $ '''./raubase -i'''		local@jack:~/svn/robobot/raubase/build $ '''./raubase -i'''

Jca: /* Test pattern */

2024-01-23T09:05:57Z

Test pattern

← Older revision		Revision as of 11:05, 23 January 2024
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	The camera calibration test pattern is found here: https://github.com/opencv/opencv/blob/3.4/doc/pattern.png; print it.		The camera calibration test pattern is found here: https://github.com/opencv/opencv/blob/3.4/doc/pattern.png; print it.

	[[File:pattern.png ~~\| 300px]] [[File:img_raw_1.jpg~~ \| 300px]]		[[File:pattern.png \| 300px]]

	=== Take test images ===		=== Take test images ===

Jca: /* Test pattern */

2024-01-23T09:05:43Z

Test pattern

← Older revision		Revision as of 11:05, 23 January 2024
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	The camera calibration test pattern is found here: https://github.com/opencv/opencv/blob/3.4/doc/pattern.png; print it.		The camera calibration test pattern is found here: https://github.com/opencv/opencv/blob/3.4/doc/pattern.png; print it.

	[[File:pattern.png \| 300px]] [[File:img_raw_1.jpg]]		[[File:pattern.png \| 300px]] [[File:img_raw_1.jpg \| 300px]]

	=== Take test images ===		=== Take test images ===